"Long ago it was said
that 'one half of the world does not know how the
other half lives.' That was true then. It did not
know because it did not care. The half that was
on top cared little for the struggles, and less
for the fate, of those who were underneath, so long
as it was able to hold them there and keep its own
seat."[18]

Riis wrote How the Other
Half Lives to call attention to the living conditions
of more than half of New York City's residents.
He described the cheap construction of the tenements,
the high rents, and the absentee landlords. He lamented
the city's ineffectual laws and urged private enterprise
to provide funding to remodel existing tenements
or build new tenements.[19]

Why
the Book Was PopularHow the Other Half Lives
was a publishing success, selling eleven editions
in five years.[20]
The book was popular for
the following reasons:

A few years before its publication,
Charles Loring Brace's The Dangerous Classes
in New York and Twenty Years' Work Among Them
and James D. McCabe's Lights and Shadows of
the Great City had placed the plight of the
poor and the dangers of the urban environment
in the minds of the middle and upper classes.